Generally, meteorological radars measure precipitation by transmitting radio waves over 360° around the radar concerned and receiving reflection wave (echo) signals caused by the transmitted radio waves reflecting on cloud or rain. The reflection wave signals contain not only echo components of cloud or rain that are observation targets, but also static clutter components that are unnecessary reflection wave components caused by the transmitted radio waves reflecting on static object(s) that is not the observation target. The static clutter components mainly contain ground clutter components that are reflection wave signal components of land.
Such static clutter components cause degradation in accuracy of rain amount calculation in meteorological observation. Therefore, conventional meteorological radars are provided with signal processing devices that perform Moving Target Indicator (MTI) processing so as to suppress such static clutter components (e.g., see JP2011-169829A).
Here, in the MTI processing, a difference in intensity between a latest reflection wave signal and a reflection wave signal previous to the latest reflection wave signal by one sample is obtained, and echo components having low frequencies, in other words, static clutter components are suppressed.
However, with such a conventional signal processing device that performs the MTI processing, when the static clutter components are to be suppressed, there is a disadvantage that the echo components of cloud or rain which move comparatively slow are also suppressed, and it is difficult to improve the accuracy of rain amount calculation in meteorological observation.